Download HTM304-4-Database Processing

Introduction to Management Information Systems
Chapter 4 Database Processing
HTM 304
Fall 07
Learning Objectives
Know purpose of database processing
List components of a database system
Understand important database terms
Know elements of the entityrelationship model
Understand general nature of database
design
2
Purpose of a Database
Keep track of things
with more than one theme
3
One Theme Spread Sheet
4
Multi-theme Database
All three records for one student
(student is the link of different themes)
Student
Score
Email
records
office
visits
5
Database Hierarchy
Bytes: the basic elements which compose of database
Fields (Columns). Name, number or characters that describe an
aspect of a business object or activity.
e.g. Student Numbers, Student Names, Midterm Scores, etc.
Record (Rows). Collection of related data fields.
e.g. 000054323
Jenny White
89.
File (or Table). Collection of related records.
e.g. Student Score Table, Student Office Visit Table, Student Email
Record Table
Database. Collection of integrated and related files + Relations
between (among) tables + structure of data.
The relations and structures are called metadata
6
Components of Database
Tables or Files
+
Relationships among Rows in Table
+
=
Database
Metadata
How to effectively organize and process raw data is the key
to a successful database design and an Information System
design.
7
Student Table
Records/Rows
Columns/Fields
8
Poorly Designed Table
Common Practice in Excel
In Database Design, the record will be split into 2 records:
Jones Feb 1, 2002
[email protected] 100
Jones Feb 1, 2002
[email protected] 100
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Pros and cons?
Finance
Accounting
Relationships
The records in different tables are connected
by certain relationships – relational databases
Key – column or group of columns
that identifies a unique row in a table
For example: Student Number is key of Student
table
The key insures no repeated records
Every table MUST have a key
Foreign key – non-key column or field in one
table that links to a primary key in another
table
10
Student Number in Email and Office_Visit tables
Foreign keys link records from different tables
together as one compound record
Examples of Relationships
Foreign Key
Key
Foreign Key
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Review Components
Tables or Files
+
Relationships among Rows
+
Metadata
12
=
Database
Metadata
Metadata are data that describe data (Format, Field Properties, etc.)
Makes databases much more useful
No one needs to guess, remember, or record what is in database
Make databases easy to use for authorized and unauthorized
purposes
13
Exercise: Use Access to setup a data table
Create a database file (*.mdb)
Create table in design view
All tables are in one database file
First create the table in design view
Specify the fields (column headers)
Specify the types of the fields, and other properties
Specify which field is the key!
Finish design view -- Close the design view
Fill in records in the table
Double click the table to enter editing view
Enter records
Try enter repeated keys, it won’t let you! Why?
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DB Application Systems Components
Pure database data correct,
but raw form not pertinent
or useful
DB applications make DB data
accessible and useful
Users employ DB applications
Forms
Formatted reports
Queries (SQL language)
Application programs
Each calls on DBMS to
process DB tables
15
DB Application System Components
DBMS (Database Management System)
A program used to create, process, and
administer a database.
Database developers use the DBMS to
create tables, relationships, and other
structures in the database.
16
Enterprise DBMS
Process large organizational and workgroup databases
Support many, perhaps thousands, of users and many different
database applications
Support 24/7 operations and can manage dozens of different
magnetic disks with hundreds of gigabytes or more data
IBM’s DB2, Microsoft’s SQL Server, and Oracle are examples of
enterprise DBMS products
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Personal DBMS
Designed for smaller, simpler database applications.
Used for personal or small workgroup applications that
involve <100 users, normally fewer than 15
Bulk of personal databases have only a single user
Microsoft Access only available personal DBMS
18
Language used in DBMS
SQL: Structured Query Language
An international standard language for processing a database:
Data Manipulation/Definition and Data Queries
Data Manipulation
INSERT INTO StudentTable ([Student Number], [Student
Name], Hw1, Hw2, MidTerm) VALUES (1000, ‘Joe Black’, 90,
85, 88)
UPDATE StudentTable SET MidTerm = ’90’ WHERE Student
Number = ‘1000’
DELETE FROM StudentTable WHERE MidTerm = NULL
Data Queries: See later.
19
Exercise:
Below shows the original table.
Write down the resulting table after executing the
following SQL command:
UPDATE StudentTable SET LetterScore = ’A’ WHERE Score >= ‘90’.
Original Table: StudentTable
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StudentNumber
StudentName
Score
LetterScore
1000
Justin Frank
89
--
2000
Dennis Wilson
60
--
3000
Sheldon Benson
92
--
4000
Gordon Black
87
--
5000
Jimmy Foxx
96
--
Exercise: write down all the other letter scores based on certain criterion.
DB Application System Components
21
Database Applications:
collection of forms, reports,
queries, and application
programs that process a
database.
A database may have one
or more applications, and
each app. may have one
ore more users…(Page 84)
DBMS
DBMS (Database Management System)
A program used to create, process, and
administer a database.
Database developers use the DBMS to
create tables, relationships, and other
structures in the database.
Multiple Database Applications
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Think how the school uses student information?
Form – A structured way to edit and view data
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Example Student Report
24
Read Only. No Editing
Query
Use SQL to search through the database and
produce certain results.
SELECT (certain attributes) FROM (certain database tables)
WHERE (conditions)
SELECT STUDENT Name, MIDTERM
FROM STUDENTTABLE
WHERE MIDTERM>90
25
Exercise:
Write down the results when using the following query
command on the following original data table:
SELECT MIDTERM FROM STUDENTTABLE WHERE MIDTERM>90
SELECT Student Name FROM STUDENTTABLE WHERE MIDTERM<70
26
SELECT Student Name, Student Number, HW1, HW2, MidTerm FROM
STUDENTTABLE WHERE MidTerm > (HW1+HW2)/2
DB Application System Components
27
Database Development Process
E-R Modeling: High level blueprint
defining how data are stored
structurally in the system
Define users’ need
through interview
28
E-R Modeling
E-R Model: a detailed, logical representation of the data
for a business. To document rules and policies of an
organization that govern data.
29
Components in E-R Model
Entity – something users want to track
Examples Order, Customer, Salesperson, Item
Some entities represent physical object,
such as an Item or Salesperson
Other entities represent a logical
construct of transaction, such
as Order or Contact
Entities have attributes that describe
characteristics of the entity
Example attributes of Salesperson are
SalespersonName, Email, Phone, etc.
30
Entities (cont)
Entities have identifier, an attribute
(or group of attributes) whose value is
associated with 1 & only 1 entity instance
OrderNumber is the identifier of Order, because only 1
Order instance has given value of OrderNumber
CustomerNumber identifier of Customer
If each member of sales staff has unique
name, then SalespersonName is an
identifier of Salesperson
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Student Data Model Entities
32
Relationships
Connects identities, allow cross entity search
A line is used to represent a relationship between two
entities
33
Three basic types of relationships
One-to-one:
One student can buy only one permit
One permit can only
purchased by one student
One-to-Many:
One instructor can teach many
courses
A course can only be taught by one
instructor
Student
Parking permit
Student ID
Name
DoB
Address
…
Parking Permit #
Date of Purchase
Type of Permit
Expiration Date
…
instructor
Instructor ID
Name
Department
Office
…
Course
CRN
Course Title
Classroom
Credit
…
Crow’s foot = Many
Many-to-Many:
One student can take more than one
course
34
A course can be registered by
multiple students
Student
Student ID
Name
DoB
Address
…
Course
CRN
Course Title
Classroom
Credit
…
Exercise
Who defines the relationships?
35
Exercise:
Exercise 22 a) (Page 105)
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Opposing Forces Guide:
No, Thanks, I’ll Use a Spreadsheet
I’m not buying all this stuff about databases.
“I’ve tried them and they’re a pain-way too complicated to set up, and
most of the time, a spreadsheet works just as well.”
“No, unless you are a General Motors or Toyota, I wouldn’t mess with a
database.”
“You have to have professional IS people to create it and keep it
running.”
“Besides, I don’t really want to share my data with anyone.”
“I work pretty hard to develop my client list.”
“Why would I want to give it away?”
“When I want something, I use Excel’s Data Filter.”
“I can usually get what I need.”
“Of course, I can’t still send form letters, but it really doesn’t matter.”
37
“I get most of my sales using the phone, anyway.”
Database Security
The firewall, a computing device located
between a firm’s internal network and
external networks, prevents
unauthorized access to the internal
network.
For the best security, the DBMS
computer should be protected by a
firewall, and then all other security
measures should be designed as if the
firewall has been breached.
38
Database Security (cont)
All operating systems and DBMS patches should be
installed as soon as they become available.
No one other than authorized operations personnel should
be able to directly access the computer that runs the
DBMS.
The computer running the DBMS should be secured behind
locked doors, and visits to that room should be recorded in
a log.
Most DBMS products log failed attempts to sign on and
produce other usage reports as well.
The database administrator (DBA) should periodically
monitor such logs and reports for suspicious activity.
39
Database Security (cont)
All major DBMS products have extensive, built-in
security features.
These features allow for the definition of user accounts
and user roles.
Each user account belongs to a specific person.
A role is a generic employee function, such as payroll clerk
or field salesperson.
Once an account is defined, it can be assigned specific
permissions, and it can also be assigned particular roles.
It is important to have a plan of action for security
emergencies.
Disaster Recovery Plan (85%)
Business Continuity Plan (<15%)
The steps to be taken vary from database to database.
40
Ethic Guide: Nobody Said I Shouldn’t
Kelly make a backup copy of his company’s
database on CD and took it home and
installed it on his home computer.
While performing queries on the database, he
found customer order information and focused
in on his friend Jason’s customer order entries.
Kelly noticed that Jason gave huge discounts
to Valley Appliances but not to his other
customers.
At an after work gathering, Kelly asked Jason about the Valley
Appliances discount telling him what he had been doing.
41
When Kelly returned to work, he was fired
Class 2: E-R Modeling and Database Lab
E-R Data Model
The most popular technique for creating a data model.
E: entity (things)
R: relationship (among the entities)
+ business rules restricting the flow of the data
Data Model:
Read Problem Solving Guide: (p89a)
Immanuel Kant, Data Modeler
Attempts to model the “real world”
Simply a model of what the data modeler perceives
42
5 minutes free write
Social Implications of DB:
Relate any of Kant’s ideas to what you
learned from reading “For Some, Online
Persona Undermines Resume”
PRINT your name on Free Write and hand it
in
43
More exercise
Book 23 a) Create a E-R Diagram to relate all the information in the form
44
Translating E-R diagram into Tables (1:N)
Key
Step 1: Create
one table for
each entity
Key
45
Translating E-R diagram into Tables (1:N)
Step 2: Add Foreign Key Column to the “many entity” to
represent relationship
46
Step 3: edit relationship
Go to Tools  Relationships
Add two entities
Drag the “advisor name” of advisor table to the “advisor name” of
student table.
Close relationships
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Many-to-Many Relationship
Now the rule changed
One advisor can supervise many students
One student can have many adviser
One student must have at least one advisor
One advisor can have no student
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Foreign Key doesn’t work for N:M relationship
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Solution
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Exercise:
Revise the relationship of previous exercise in
Access and input the above records
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1:1 Relationship
How to convert into tables?
52
Exercise
Based on your E-R diagram in 23(a), construct tables
and relationships in Access. Add at least three records for
each table.
53
Importance of User Review
Users are the final judges of what data the database
should contain and how records relate to one another
Easiest time to change database structure is during data
modeling stage
Once database has been constructed, loaded with data,
and application forms, reports, queries, and application
programs created, changing a relationship means
weeks of work!
54
How should you review as a user? (Cont)
When database developed for your use, you must carefully review
data model
If you don’t understand any aspect of it, ask for clarification until
you do
Data model must accurately reflect your view of business
Do not proceed unless you are 100% comfortable with the model
55
Key Terms and Concepts (Cont.)
57
Access
Field
many-to-many relationship
Attribute
File (Table)
Oracle
Byte
Foreign key
Query
Column
Identifier
Personal DBMS
Crow’s foot
Key
Record
Database
Maximum cardinality
Relationship
Database application system
Meta Data
Report
DBMS
Minimum cardinality
Row
E-R data model
one-to-many relationship
SQL Server